Sync generic Customer.io destination fixes upstream

[jcpsimmons]

Summary

This upstreams the generic Customer.io destination behavior that should live in segmentio/action-destinations, instead of staying only in Customer.io's fork.

This PR is intentionally limited to generic Customer.io behavior that benefits Segment users connecting to Customer.io:

• framework support for destinations to return parsed batch multi-status results
• Customer.io Track API multi-status parsing in the shared destination
• decimal timestamp tolerance in Customer.io timestamp parsing
• the generic reserved-event preset/default-subscription updates that our fork already exposes

Why

Customer.io currently carries a forked Customer.io destination in customerio/cdp-action-destinations and a CDP-side wrapper in customerio/cdp.

For CDP-4750, the goal is to shrink the fork over time:

• upstream generic destination fixes here
• keep Customer.io-only runtime overrides in customerio/cdp
• leave only temporary fork-only deltas in customerio/cdp-action-destinations

The main generic gap this PR addresses is Track API batch handling. Our fork already knows how to parse Customer.io's per-item batch errors and surface them as multi-status results instead of treating the entire batch as a flat success. That behavior should exist upstream because it is part of the shared Customer.io API contract, not a Customer.io-internal deployment detail.

Changes

• Adds MultiStatusResponse / ResultMultiStatusNode support in the actions core so a destination can return parsed per-item batch results.
• Updates the Customer.io destination sendBatch() helper to parse Track API 207 Multi-Status responses and 200 responses that still contain an errors array.
• Allows decimal numeric timestamps to pass through Customer.io timestamp normalization unchanged.
• Brings the upstream Customer.io preset/default-subscription surface closer to the generic preset set already exposed in our fork:
  • Delete Device
  • Delete Relationship
  • Delete Person
  • Delete Object
  • Merge People
  • Suppress Person
  • Unsuppress Person
  • reserved-event exclusions for device/object events in Track Event
  • Device Created or Updated in Create or Update Device
• Adds focused Customer.io tests for the preset surface and Track API multi-status parsing helpers.

Related PRs

• Fork parity / transitional Customer.io fork PR: https://github.com/customerio/cdp-action-destinations/pull/195
• CDP wrapper PR: https://github.com/customerio/cdp/pull/4523

Verification

I could not run the Segment repo test suite in this environment because local dependency installation fails on private Segment packages (@segment/remote-service-client and control-plane-service-js-client).

The code paths ported here are taken from behavior already running in Customer.io's fork, and I added matching upstream tests in this PR for those same code paths.

[jcpsimmons]

Dependency map for CDP-4750:

• segmentio/action-destinations#3654 is the upstream source-of-truth PR for generic Customer.io destination behavior.
• customerio/cdp-action-destinations#195 is the transitional fork PR that keeps our forked manifest/presets aligned and retains the fork-only Report Content Event preset.
• customerio/cdp#4523 is the CDP wrapper PR for cio-customerio only.

Merge intent:

• this PR owns generic shared behavior
• #195 should not be used as the long-term home for shared runtime fixes
• #4523 should remain wrapper-only

Links:

• Fork PR: https://github.com/customerio/cdp-action-destinations/pull/195
• CDP PR: https://github.com/customerio/cdp/pull/4523

[jcpsimmons]

Superseded by the smaller draft split for CDP-4750:

• STRATCONN-6833 - [Customer.io] - Track API batch multi-status responses #3657 Track API batch multi-status parsing
• Preserve decimal Customer.io timestamps #3656 decimal timestamp normalization
• Align Customer.io preset subscriptions with reserved events #3655 preset/default-subscription parity

Closing this larger draft to avoid duplicate review paths and stale conflict noise.